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<a name="EXECUTE_005fCOMMAND_005fLINE"></a>
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<a name="EXECUTE_005fCOMMAND_005fLINE-_002d_002d_002d-Execute-a-shell-command"></a>
<h3 class="section">8.100 <code>EXECUTE_COMMAND_LINE</code> &mdash; Execute a shell command</h3>
<a name="index-EXECUTE_005fCOMMAND_005fLINE"></a>
<a name="index-system_002c-system-call"></a>
<a name="index-command-line"></a>

<dl compact="compact">
<dt><em>Description</em>:</dt>
<dd><p><code>EXECUTE_COMMAND_LINE</code> runs a shell command, synchronously or
asynchronously.
</p>
<p>The <code>COMMAND</code> argument is passed to the shell and executed (The
shell is <code>sh</code> on Unix systems, and <code>cmd.exe</code> on Windows.).
If <code>WAIT</code> is present and has the value false, the execution of
the command is asynchronous if the system supports it; otherwise, the
command is executed synchronously using the C library&rsquo;s <code>system</code>
call.
</p>
<p>The three last arguments allow the user to get status information.  After
synchronous execution, <code>EXITSTAT</code> contains the integer exit code of
the command, as returned by <code>system</code>.  <code>CMDSTAT</code> is set to zero
if the command line was executed (whatever its exit status was).
<code>CMDMSG</code> is assigned an error message if an error has occurred.
</p>
<p>Note that the <code>system</code> function need not be thread-safe. It is
the responsibility of the user to ensure that <code>system</code> is not
called concurrently.
</p>
<p>For asynchronous execution on supported targets, the POSIX
<code>posix_spawn</code> or <code>fork</code> functions are used.  Also, a signal
handler for the <code>SIGCHLD</code> signal is installed.
</p>
</dd>
<dt><em>Standard</em>:</dt>
<dd><p>Fortran 2008 and later
</p>
</dd>
<dt><em>Class</em>:</dt>
<dd><p>Subroutine
</p>
</dd>
<dt><em>Syntax</em>:</dt>
<dd><p><code>CALL EXECUTE_COMMAND_LINE(COMMAND [, WAIT, EXITSTAT, CMDSTAT, CMDMSG ])</code>
</p>
</dd>
<dt><em>Arguments</em>:</dt>
<dd><table>
<tr><td width="15%"><var>COMMAND</var></td><td width="70%">Shall be a default <code>CHARACTER</code> scalar.</td></tr>
<tr><td width="15%"><var>WAIT</var></td><td width="70%">(Optional) Shall be a default <code>LOGICAL</code> scalar.</td></tr>
<tr><td width="15%"><var>EXITSTAT</var></td><td width="70%">(Optional) Shall be an <code>INTEGER</code> of the
default kind.</td></tr>
<tr><td width="15%"><var>CMDSTAT</var></td><td width="70%">(Optional) Shall be an <code>INTEGER</code> of the
default kind.</td></tr>
<tr><td width="15%"><var>CMDMSG</var></td><td width="70%">(Optional) Shall be an <code>CHARACTER</code> scalar of the
default kind.</td></tr>
</table>

</dd>
<dt><em>Example</em>:</dt>
<dd><div class="smallexample">
<pre class="smallexample">program test_exec
  integer :: i

  call execute_command_line (&quot;external_prog.exe&quot;, exitstat=i)
  print *, &quot;Exit status of external_prog.exe was &quot;, i

  call execute_command_line (&quot;reindex_files.exe&quot;, wait=.false.)
  print *, &quot;Now reindexing files in the background&quot;

end program test_exec
</pre></div>


</dd>
<dt><em>Note</em>:</dt>
<dd>
<p>Because this intrinsic is implemented in terms of the <code>system</code>
function call, its behavior with respect to signaling is processor
dependent. In particular, on POSIX-compliant systems, the SIGINT and
SIGQUIT signals will be ignored, and the SIGCHLD will be blocked. As
such, if the parent process is terminated, the child process might not be
terminated alongside.
</p>

</dd>
<dt><em>See also</em>:</dt>
<dd><p><a href="SYSTEM.html#SYSTEM">SYSTEM</a>
</p></dd>
</dl>



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